Liquid level alarm system

ABSTRACT

A liquid level alarm system is activated when liquid in a container falls below a predetermined level. The system contains an alarm located outside the container. The alarm is electrically connected to a switching device. The switching device may have a push-down button located on the top, an &#34;on-off&#34; switch located on the side, or a sliding switch located on the side. When the switch is pushed down, the switching device activates the alarm. In one embodiment, the container has a vertically positioned rod adjacent the switching device. There is a float slidably connected to the rod by a connecting rod and hook. The float rises and falls with the level of the liquid. On the side of the rod opposite the float there is a switch contact which makes contact with the switch when the level of the liquid falls below a predetermined level and the float is no longer supported by the liquid. In another embodiment, a float is positioned on tracks so that the switch will be forced down by the float when the liquid level falls below a predetermined point. The tracks contain slots allowing rollers attached to the float to freely rise and fall with the liquid level while maintaining its position relative to the switch. The switching device may be electrically connected to a motor which, when activated, changes a valve in an inlet pipe from the open position to the closed position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of Ser. No. 08/705,756, filedAug. 30, 1996, which is a continuation in-in-part of Ser. No.08/579,589, filed Dec. 26, 1995, now U.S. Pat. No. 5,610,591.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is directed to alarm systems and automatic shut-offsystems which will be activated when the liquid in a container fallsbelow a predetermined level.

2. Description of the Related Art

The prior art is aware of devices which signal the rising of liquids invarious containers above predetermined levels. French Pat. No. 2 254 016and U.S. Pat. Nos. 4,962,370; 4,988,978; 5,006,834; and 5,028,910 areexamples of such devices. U.S. Pat. No. 4,988,978 is also adapted toemit a signal when the liquid falls below a predetermined level. Thedevice of this patent is complex and is not easily adjustable to providefor varying predetermined levels of the liquid. Also, the device isuseable only when the container is fitted with the particular coverdefined in the patent, and cannot be retrofitted into existingcontainers. U.S. Pat. No. 4,968,976 teaches an alarm kit useful foremitting an alarm when water in a container falls below a predeterminedlevel. The alarm of this device is triggered by the pivoting of an armagainst a spring to close an electrical circuit. The alarm of thisdevice must be in the same housing as the activator for the alarm. Thus,the alarm could not be in a unified security system. For purposes ofthis invention, a unified security system is considered to be a systemin which a plurality of individual monitoring devices supply data to acentral location at which the status of the individual devices ischecked and action can be initiated if an alarm is triggered. The devicemust be mounted outside the container. Thus, the device could not beused on an outside storage tank where ice or snow would render thedevice inoperative. Further, the float is connected to the arm by along, flexible line which would get wrapped around any objects in thecontainer. Therefore, the device could not be used as an alarm system ina commode or other container which contains elements which would serveto snare the line.

The prior art is aware of automatic flood control valves which, upon thedetection of leakage in a system, shut a valve in the intake pipe, asseen in U.S. Pat. No. 4,659,063 to Veillette et al. Petcocks are knownfor the purpose of controlling liquid flow from containers, as seen inU.S. Pat. No. 3,931,954 to Guzzetta.

The inventor's earlier invention disclosed in U.S. Ser. No. 08/579,589,now U.S. Pat. No. 5,610,591 is directed to a liquid level alarm systemin which an alarm is activated when liquid in a container falls below apredetermined level. The system contains an alarm which is mountedoutside the container, which alarm is electrically connected to anactivation device which is contained within a housing which may beinside or outside the container. A single-pull switch arm is connectedto the activation device and protrudes from the housing. One end of aline is attached to the distal end of the arm and the other end of theline is wound about a spring reel mounted on an axle connected to afloat. When the surface of the liquid is between a predetermined upperand lower level, the spring reel maintains the line taut directly belowthe switch arm. The line is of such a length that should the liquid inthe container drop below a predetermined level, the float will no longerbe supported by the liquid, and the weight of the float will pull thearm down to activate the alarm. This system is quite satisfactory forits intended purpose. It may be used in small containers such ascommodes, or large containers such as oil tanks. It may have an alarmattached directly to the container, or the alarm may be part of aunified system. The predetermined lower level for the liquid may bereadily established by adjusting the length of line attached to thespool. The present invention is intended to be an improvement over theearlier invention in that it shares the same benefits and is of simplerdesign.

SUMMARY OF THE INVENTION

The present invention is directed to an alarm system which will beactivated by the falling of liquid in a container below a predeterminedlow point. The alarm system contains an alarm positioned outside of thecontainer and an electrical switching means positioned inside thecontainer at the level of the predetermined lower level of the liquidfor activating the alarm. In one embodiment of the invention, theswitching means has an upwardly extending push-button switch located atthe top or side of the switching means. In another embodiment of theinvention, the switching means has a vertically sliding switch locatedat a side of the switching means. There is an electrical connectionbetween the switching means and the alarm. In one embodiment of thepresent invention, there is a bow hook rod which is non-circular incross-section and which extends vertically in the container near theswitching means. In another embodiment of this invention, there is apair of tracks positioned vertically within the container and extendingbetween a point near the predetermined high point of the liquid surfaceto point near the predetermined low point of the liquid surface, whichtracks contain slotted surfaces. The system of this invention contains afloat suitable for floating on the surface of the liquid and which is ofsuch a weight as to be capable of actuating the switching means when theweight of the float rests upon the push button switch or verticallysliding switch of the switching means. In one embodiment of thisinvention, a bow hook is slidably attached to the bow hook rod. In thisembodiment, a connecting rod connects the float to the bow hook to allowthe float to rise or fall with the level of the liquid but maintain itsposition near the switching means. In this embodiment, a switch contactis connected to the bow hook opposite the connecting rod and the float,which switch contact will transfer the weight of the float to the pushbutton actuator or vertically sliding switch when the level of theliquid falls below a predetermined level, thus activating the alarm. Inanother embodiment of this invention, the float contains at least twoflat sides connected to rollers and is positioned so that the rollersfit into the slots in the tracks allowing the float to move freelyvertically along the tracks as the liquid level changes. The floatcontains an end which overhangs the push button switch or verticallysliding switch and will push down the switch to activate the alarm whenthe level of the liquid falls below the predetermined lower liquid levelpoint. In one embodiment of this invention, the activation of theelectrical switching means will activate a valve in the intake pipe ofthe container to automatically shut off the intake pipe.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross-sectional view of one embodiment of the alarm systemof this invention in combination with a container.

FIG. 2 is a side view of the electrical switching means, switch contact,bow hook, float, connecting rod, and bow hook rod of the presentinvention showing these elements of the invention in greater detail.

FIG. 3 is a top plan view showing the float, connecting rod, bow hook,switch contact, and bow hook rod in detail.

FIG. 4 is a vertical cross-sectional view from the front of anotherembodiment of the alarm system of this invention in combination with acontainer.

FIG. 5 is an elevational side view showing the connection of a track ofone embodiment of this invention to the back of the container.

FIG. 6 is an elevational side view showing the connection of a track ofone embodiment of this invention to the bottom of the container.

FIG. 7 is a elevational side view of a float of the present inventionmounted on tracks, one side of the tracks being partially removed forclarity.

FIG. 8 is a top plan view of a float of one embodiment of the presentinvention mounted on tracks with rollers.

FIG. 9 is a schematic view of the electrical system for the alarm andshut-off valve of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be more particularly described with reference tothe above drawing, like numerals referring to like features throughout.

Referring to FIGS. 1-9, an alarm system 1 according to this invention isshown. A container 2 forms a reservoir which contains a liquid 3 whichhas a surface level 4 which fluctuates between a predetermined highpoint (not shown) and a predetermined low point (not shown). Thecontainer 2 has a bottom 5 having inner 6 and outer 7 surfaces and atleast one wall 8 having inner 9 and outer 10 surfaces. The container 2may be made of conventional materials, such as ceramic, plastic, ormetal. The size of the container 2 is not critical in the context of thepresent invention, and may be adapted for use inside or outsidebuildings.

The nature of the liquid 3 which may be used in the present invention isbroad in scope. The liquid 3 may be water when the container 2 is a hotwater heater, a commode, or a storage tank. Likewise, because theto-be-described electrical switching means is hermetically sealed, theliquid 3 may be a hydrocarbon or other flammable or explosive liquid.The liquid 3 has a surface level 4 which is intended to fluctuatebetween a predetermined high point and a predetermined low point. Thepurpose of the system 1 is to give notice when the liquid 3 falls belowthe predetermined low point because of normal usage or because of arupture in or near the bottom 5 of the container 2.

The system 1 contains an alarm means 11 outside the container 2. Thealarm means 11 may be attached directly to the container 2 or may be ata distance therefrom. The alarm means 11 may be a bell, siren, or otheraudible device. Alternatively, the alarm means 11 may be a light orother visible signal. The alarm means 11 contains the power source 12for the alarm system or the power source may be in a separate container.The alarm means 11 may be incorporated into a unified security system(not shown). For purposes of this invention, a unified system is one inwhich the alarm means 11 is positioned at a point distant from thecontainer, usually in combination with other alarm means so thatnumerous security situations may be monitored simultaneously.

The alarm system 1 also contains an electrical switching means 13 whichis positioned inside the container 2 at a vertical position which isnear the predetermined low point of the liquid surface 4. The switchingmeans 13 has a top 14, a bottom 15, and at least one side 16. Thehorizontal positioning of the switching means 13 is not critical.Preferably, it is attached to an inner surface 9 of the wall 8 of thecontainer 2 by conventional means, such as screws, bolts, VELCRO, andsnap-on supports. The switching means 13 is so constructed as to bereadily repositioned as the determination of a low point of the surfacelevel 4 of the liquid 3 changes. When the predetermined low point isnear the bottom 5 of the container 2, the electrical switching means 13may be attached to the bottom 5 of the container 2. The electricalswitching means 13 is hermetically sealed to avoid damage to theswitching means 13 and to provide safety in those instances when theliquid 3 inside the container 2 is flammable or explosive. The design ofthe switching means 13 is simple. In one embodiment, the switching meanscontains a push button 17 which is pushed down by the weight of thefloat 18. The switching means 13 contains an open circuit when thebutton 17 is in the "up" position. When the button 17 is pushed down,the circuit is closed, actuating the switching means 13 and activatingthe alarm means 11 by way of a connecting means 19 for electricallyconnecting the switching means 13 and the alarm means 11. Preferably,the push button 17 is on the top 14 of the switching means 13.Alternatively, the button 17 may be located on a side 16. The means 19for connecting the switching means 13 to the alarm means 11 ispreferably insulated electrically conductive wire. In anotherembodiment, the switching means 13 contains a vertically sliding switch20. When the switch 20 is in the "up" position, the circuit is open.When the switch 20 is pushed down by the weight of the float 18, thecircuit closes, and the alarm means 11 is activated.

In one embodiment, a bow hook rod 21 is located adjacent to theelectrical switching means 13. Preferably, the bow hook rod 21 isattached to a wall 8 of the container 2 by a hook-shaped upper portion22 of the bow hook rod 21. For large containers 2, the bow hook rod 21is attached to a base plate 35, which plate is secured to the innersurface 6 of the bottom 5 of the container 2. The bow hook rod 21 isnon-circular in cross-section. Thus, it may be rectangular, oval,semicircular or circular with at least one notch or protrusion.

The bow hook 23 is slidably attached to the bow hook rod 21. The bowhook 23 has the same relative shape as the bow hook rod 21, but isslightly larger in cross-section than the bow hook rod 21. Exactdimensions are not critical, however one-sixteenth of an inch ofclearance has been found to be preferable. Because of this relationshipof shapes, the bow hook 23 is able to maintain its relative position asit travels vertically along the bow hook rod 21.

A float 18 having a proximal end 24 and a distal end 25 is attached tothe bow hook 23 by way of a connecting rod 26. This attachment is at aside of the bow hook rod 21 opposite the electrical switching means 13.The float 18 is of any geometrical shape, although boat-shaped,spherical, and hexahedral are preferred, The float 18 may be solid orhollow and may be made of any conventional material. When the float 18is hollow, a suitable amount of ballast 27 may have to be added toenable the weight of the float 18 to be sufficient to push the pushbutton 17 or the vertical slide 20 into the "down" position. The float18 must be so constructed so as to float in the liquid 3 which is heldin the container 2. Also, the float 18 must have sufficient weight sothat when the float 18 is no longer supported by the liquid 3, theweight of the float 18 is sufficient to press down the button 17 20 onthe electrical switching means 13.

A contacting means 28 is attached to the bow hook 23 opposite theconnecting rod 26 and float 18. As the level of the liquid 3 in thecontainer 2 falls below the predetermined level, the contacting means 28comes in contact with the button 17 on the electrical switching means 13and presses the button 17 down so as to close the circuit in theelectrical switching means 13. Preferably, the contacting means 28, bowhook 23, connecting rod 26 and float 18 are constructed of the samematerial.

As an alternative, a float 18 having a flat bottom may be positioneddirectly above the button 17 on the electrical switching means 13. Inthis situation, the float 18, itself, pushes down the button 17,eliminating the need for a separate contacting means 28.

In a separate embodiment of this invention, the bow hook rod 21 isreplaced by a pair of tracks 29. Each track 29 contains a lower end 30,an upper end 31, and a slot 32 which is able to hold rollers 33connected to the float 18. The tracks 29 may be connected to the bottom5 of the container 2 by a holding means. A preferred holding means isattached to the bottom 5 by welds, glue, or screws and contains a baseplate 35 having an upraised protrusion 34 onto which the track 29 fitssnugly. The track 29 is connected to the wall 8 of the container 2 by anadjustable upper holding means 36. This holding means comprises a distalend 37 containing a slot 38 which fits over the wall 8, a first, outersection 39, and a second, inner section 40. The inner section 40slidably fits into the outer section 39 allowing for the distance of thetrack 29 from the wall 8 to be easily adjustable. When properlyadjusted, the inner 40 and outer 39 sections are secured in place. Awing bolt 41 is an example of means for securing these sections. By thismeans, the upper end 31 of the track 29 maintains rigidity and properplacement while avoiding contact with the walls 8 of the container 2.

In this embodiment, rollers 33 of the float 18 fit loosely into theslots 38 in the tracks 29 and thus enable the float 18 to freely travelvertically with the rise and fall of the liquid.

The float 18 contains an overhang 42. The positioning of this overhang42 is not critical, but is preferably near the top of the float 18. Thisoverhang 42 is so positioned that it will press down upon the pushbutton switch 17 or vertical slide switch 20 when the level of theliquid 3 is such that the switch 17 20, rather than the liquid 3, bearsthe weight of the float 18.

Upon closing of the circuit in the switching means 13, the alarm 11 isactivated through connecting means 19. A separate electrical connectingmeans 43 connects the switching means 13 with a motor 44. The motor 44contains a rotatable shaft 45 which is attached through a connectingline 46 to the handle 47 of a petcock 48. The petcock 48 is sealed into,and may freely rotate in, inlet pipe 49. Upon closing of the circuit inswitching means 13, the motor 44 is activated, turning the shaft 45 andturning the handle 47 of the petcock 48. This rotates the petcock 48 90°from the open position to the closed position, thus automaticallyturning off the inflow of the liquid in the inlet pipe 49.

It can readily be seen that the system of this invention is simple inconstruction, but may be adjusted to give an alarm and cut off theinflow of liquid at a precise predetermined level of liquid in acontainer.

It will be appreciated that modifications can be made in the details ofthe invention without departing from the inventive aspect of theinvention, which is set forth in the following claims.

I claim:
 1. An alarm system for use in a container having a top havinginner and outer surfaces, a bottom having inner and outer surfaces, andat least one wall having an inner and outer surface, which containercontains a liquid having a surface level which fluctuates between apredetermined high point and a predetermined low point; said systemcomprising:(a) an alarm means to be positioned outside the container;(b) A pair of tracks having an upper end and a lower end to bepositioned vertically within the container and extending at leastbetween a point near the predetermined high point of the liquid and apoint near the predetermined low point of the liquid; (c) an electricalswitching means to be positioned inside the container near thepredetermined low point of the liquid surface, said switching meanshaving a top, a bottom, and at least one side, the top or the side ofsaid switching means having a switch, which switch is capable of beingpushed vertically downwardly to actuate an activating mechanismcontained within the switching means which, in turn, activates thealarm; (d) a connecting means for electrically connecting the switchingmeans and the alarm means; and (e) a float suitable for floating on thesurface of the liquid, said float having rollers attached thereto, whichrollers fit in the tracks allowing the float to move vertically as theliquid rises and falls yet maintain its position relative to theswitching means, said float being capable of depressing the switch whenthe level of the liquid falls to a point which is sufficiently low thatthe weight of the float presses down upon the switch, the spatialcorrespondence between the float and the switch being such that thefloat comes in direct contact with the switch when the surface level ofthe liquid falls to the predetermined low point.
 2. A combinationcomprising a container and the alarm system defined in claim
 1. 3. Thecombination of claim 2, wherein the switch is on top of the switchingmeans.
 4. The combination of claim 2, wherein the switch is on a side ofthe switching means.
 5. The combination of claim 2, wherein the alarmsystem is part of a unified security system.
 6. The combination of claim2, wherein the alarm comprises an audible indicator.
 7. The combinationof claim 2, wherein the container is a commode reservoir, the alarmmeans is attached to the commode, and the connecting means passes fromoutside the reservoir to inside the reservoir between the top and a sideof the reservoir.
 8. The combination of claim 2, wherein the float isspherical in shape.
 9. The combination of claim 2, wherein the containerhas an inlet pipe; an electrical connecting means connects the switchingmeans to a motor containing a rotatable shaft; and the rotatable shaftis connected to a valve in the inlet pipe, which valve has an open and aclosed position, so that when the switching means is activated the valvein the inlet pipe is moved from the open position to the closedposition.
 10. The combination of claim 9, wherein the valve is a petcockvalve.